Motor brake for electric hoists



Aug. 26, 1924. 1,506,341

E. N. HESCOCJK MOTOR BRAKE FOR ELECTRIC HOISTS Filed May 19. 1923 2 Shank-Sheet 1 A TTORNE Y E. N. HESCOCK I MOTOR BRAKE FOR ELECTRIC HOISTS BY A A TTORNEY Patented Aug. 26, 1924.

UNITE ETHAN N. HESGOCK, OF \VESTFIELD, ITEN JERSEY, ASSIGNOR TO NEW JERSEY FOUN- DRY AND MACHINE COMPANY, A CORPORATION OF NEVT JERSEY.

MIOTOR BRAKE FOR ELECTRIC I-IOISTS.

Application filed May 19, 1923. Serial No. 640,156.

To all whom it may concern:

Be it known that I, ETHAN N. Hnsooox, a citizen of the United States, residing at lVestfield, in the county of Union and State of New Jersey, have made certain new and useful In'iprovements in Motor Brakes for Electric Hoists, of which the following is a specification, taken in connection with the accon'ipanying drawings.

My invention relates to an electric holst and more particularly to one provided with a secondary or auxiliary friction brake or retarding member, to prevent the coasting or spinning of that part of the hoisting mechanism which controls the operation of the first or main brake, so that the load will be held fast by the main brake, the instant that the current is cut off from the motor.

I am aware that expensive electric brakes, requiring separate Wiring, have been used for this purpose. By my invention the cost of an electric hoist can be greatly reduced, in that I employ a simple automatic secondary or auxiliary friction brake, and omit entirely the costly electric brake and its wiring.

My invention further relates to certain combinations, sub-combination and details of construction all of which will be more fully hereinafter described and pointed out in the claims.

In the drawings I have shown one embodiment of my invention, but it is of course to be understood that my invention is not to be confined to the particular embodiments shown by way of illustration.

Fig. 1 is a side elevation of an electric hoist mounted on a trolley, the I-beam track being shown in section;

Fig. 2 is a horizontal section substantially on the line 22 of Fig. 1 and on an enlarged scale;

Fig. 3 a vertical section taken on the line 3-3 of Fig. 2.

Fig. 4: is a detail view.

In the particular form of electric hoist that I have shown, by way of example, the entire electric hoist mechanism 1 is mounted upon the trolley 2 carried by the rollers 3, 3 supported by the I-beam track 4. While I have, for purpose of illustration, shown the electric hoist movable on a trolley it is, of course, to be understood that it may be fixed if desired.

This electric hoist is provided with the usual control box 5, switch 6, control cord '2', motor 8, and main axle 9. From the main axle 9 to the winding drum suitable reducing gear is employed. I have shown, for example, the main axle 9 extending entirely through the main housing 10 and into the supplemental housing 11. Keyed to the main axle 9 is a pinion 12 in mesh with the gear wheel 13 keyed upon a counter shaft 141. On this counter shaft is also keyed a pinion 15 in mesh with the gear wheel 16 which in turn is keyed to the sleeve 17 of the pinion 18 loosely mounted upon the main axle 9. This pinion 18 is in gear with the gear wheel 19, keyed on the sleeve 20 of the friction disc 21. This disc 21 is provided with female screw-threads to cooperate with the male threads 22 upon the countenshaft 23. Upon this counter-shaft is keyed a check- Washer 2 1, having a tooth 25 normally in engagement with a tooth 26 on the friction disk 21. The arrangement is such that the relative rotation of the friction disk 21 and its sleeve 20, with relation to the countershaft 23, is limited to one rotation to permit the tooth 26 to engage on either side of the tooth 25 carried by the check-washer 24; keyed on the counter-shaft 28. Mounted loosely upon the same counter-shaft 23 is another friction disk 27. A pinion 28 is keyed.

upon the shaft 28.

Between the friction disks 21 and 27 is mounted the main brake wheel 29 free to rotate in one direction. Tts periphery is provided with teeth 39 to cooperate with the fixed pawl 81 mounted on the pin 32, carried by the housing 10. Between the brake wheel 29 and the friction discs 21 and 27 I preferably mount loose friction members of any suitable material 33, 33.

In mesh with the pinion 28 is a gear wheel 84 which is loosely mounted upon the hollow sleeve shaft 35. This gear wheel 34 is provided with a sleeve 36 having arms 37, 37 to cooperate with enlar ed pockets or recesses 38, 88 (only one being shown in Fig. 2) in the winding drum 39, which is itself loosely mounted upon the hollow sleeve shaft 35.

From the mechanism so far described, when it is desired to raise a load connected to the hook 40, Fig. 1, so as to wind the rope or cable 11 upon the winding drum 39, the switch 6 of the control box 5 is operated, in any suitable manner as for example by the cord 7, so as to energize the motor 8 and operate the main shaft 9. Power is transmitted from this main shaft 9 to pinion 12, gear wheel 13 mounted upon the countershaft 14, counter-shaft 14, pinion 15 keyed upon said countershaft, gear wheel 16, loose pinion 1S, gear wheel 19, friction disc 21, and counter-shaft 23. The screw-threads be tween the friction disc 21 and the countershaft 23 cause the friction disc 21 to move laterally, or to the left of Fig. 2, and firmly grip the brake wheel 29 between the fric tion disc 21 and the friction disc 27, thereby causing the main brake wheel 29 to rotate with the friction discs 21, 27 and countershaft 23, the fixed pawl 31 idly engaging the teeth 30 on the periphery of the brake wheel as it. is moved under said pawl. The power is then transmitted through the pinion 28 fast on counter-shaft 23 to the gear wheed 34, loosely mounted upon the hollow sleeve shaft 35, and to the winding drum 39, to wind up the rope chain or cable 41 so as to lift the hook and any load that may be attached to it.

In this operation of raising the load, the main shaft 9 operates counter-cloclnvise, and the counter-shaft 14 operates clockwise, as indicated by the arrows, Figs. 2 and 3.

lVhen it is desired to lower the load, the current is reversed through the motor 8 and the main shaft 9 is reversed and made to revolve clockwise and the counter-shaft counter-clockwise. This reversing of the current and of the main axle 9 causes the r friction disc 21 to move slightly on its screw-thread on the counter-shaft 23 so as to free the brake wheel 29 of the grip of the twofriction disks 21 and 27 and of the friction members 33, 33, if they are employed. During this lowering or retrograde movement of the hook 40 and its load, the brake wheel 29 is held immovable by means of the fixed pawl 31 engaging with one of the teeth 30. Theoretically it is possible to lower the load and stop it at any desired elevation by simply cutting off the current from the motor 8 so that the brake disks 21 and 2? would instantly again clamp and hold the brake wheel 29, which is held by the fixed. pawl 31, so that further downward movement of the load, after the current is: cut off, would be impossible.

It is found in practice, however, that this is not so, for the reason that after the current is cut off the motor, the main axle 9 and the reducing gear connected therewith, will spin or coast and prevent the instant gripping of the brake wheel 29 by the friction disks 21 and 27. The result is that such electric hoisting mechanism is unsatisfactory in practice unless this spinning or coasting of the main axle 9, and its connected gearing, is stopped instantly as soon as the current is cut off the motor, for otherwise, the main brake mechanism, previously described, will. not hold the load at any fixed or determined point, but will permit the load to drift downward beyond the point desired by the operator to a greater or less distance.

To overcome this diflicult-y, very expensive electric brake mechanism have been employed to stop the coasting or spinning of the main axle 9; Not only is it necessary, in such devices, to use such an expensive electric brake, which, of course, adds materiallyto the cost of the electric hoist, but in addition thereto, extra wiring for the electric brake has to be employed.

My invention relates primarily to substituting for such an expensive electric brake a simple,eflicient and automatic friction brake, which, of course, requires no additional wiring, and which can be added to the electric hoist mechanism at minimum expense.

In the embodiment of my invention shown in the drawings, I employ my friction brake to act directly upon the main axle 9, or a secondary or auxiliary brake wheel keyed to said axle. In the particular form of my invention shown the application of the secondary or auxiliary brake is controlled by the direction of rotation of the counter-shaft 14.

Within the secondary housing 11, which is connected to the main housing 10, I key a brake wheel 46 to the main axle 9. i the end of the counter-shaft 14 I mount the clamps 47 and 48, these clamps bearing more or less upon the counter-shaft 14 by means of the bolts 49, 49, springs 50, 50 and nuts 51, 51, which adjust the friction of said clamp upon the rotating countershaft 14. These clamps 47, 48 are provided with jaws 52, 52 to receive between them the lug 53 secured on the end of the hand brake 54, the other end of which is secured to the pin 55, carried by the fixed housing 10.

In winding the ,rope, cable or chain 41 upon the winding drum 39, to raise a load attached to the hook 40, the main axle 9 rotates counter-clockwise, and the countershaft 14 operates clockwise as shown by the arrows in Fig. 3. This will cause the clamps I 47, 48 to move the lug 53 and with it the band brake 54 away from the secondary or auxiliary brake wheel 46, so that in raisii'ig a load there will be no friction or drag upon the main shaft 9. In lowering a load,

by reversing the direction of rotation of the,

main shaft 9 and the counter-shaft 14, the spinning or coasting of the main shaft 9 is instantly prevented for the reason that the counter-shaft 14 would then be rotating counter-clockwise and would cause the clamping jaws 52 and 53 to move counterclockwise and bring the band brake 54 firmly against the auxiliary or secondary brake wheel 46 then rotating clockwise. This will instantly stop the spinning or coasting of Around 1 the main axle 9, thereby permitting the load to operate the main brake, previously described at length, which will hold the load at the point or location where the current is cut off the motor and prevent it drifting downward, more or less, beyond the polnt desired by the operator. It is, of course, tc be understood that the coasting of the main axle 9, after the current is cut off, prevents the immediate application or relative movement of the screw-threads 22 cooperat ing with the female screw-threads in the friction disk 21 to instantly lock the main brake and hold the load.

lVhen it is desired to lower the hook 40, this can be readily done by reversing the motor and the shaft 9, my secondary brake mechanism not interfering with the free movement of the hook and cable 41.

In operating the electric hoist the motor is energized to raise the load and theoretically it would be possible to hold the load at any desired elevation by simply cutting off the current from the motor. Due to the coasting of the main axle 9 and the reducing gear it is found in practice that the main brake mechanism will not hold the load at any fixed or determined point, but on the contrary, will permit the load to drop, more or less, beyond the point desired by the operator.

The secondary automatic brake 54 does not engage witlr the secondary brake wheel 46 as long as the load is being raised because, at that time, the rotation of the countershaft 14 (Fig. 3) is clockwise, as shown by the arrow. As soon as the current is cut off the motor and the load starts, even so slightly, to descend, or try to descend, beyond the desired point to which it has been raised, the countershaft 14 will be moved slightly counterclockwise in the reverse direction from the arrow (Fig. 8), and instantly and automatically will actuate the brake band 54 bringing it into engagement with the secondary brake wheel 46 keyed to the shaft 9, thereby instantly stopping the spinning or coasting of the main axle 9 and the gearing, permitting the main brake to function and hold the load at the desired elevation.

It is, of course, understood that the motor actuates the shaft 9 both on raising or lowering a load attached to the hook 40. 'Ilhe secondary brake 54 is only actuated to stop the spinning or coasting of the main axle 9, and the gearing, when the current is cut off, to hold the load at any given elevation.

On raising a load the brake 54 does not contact with the brake wheel 46, so that the load is raised free of any retarding effect of this brake.

In lowering the hook 40 with its load, the direction of rotation of the counter shaft 14 is such that the brake band 54 is brought into engagement with the auxiliary brake wheel 46, but its retarding effect, against the action of the motor in reverse and the weight of the load is negligible. Its function is not to hold the load or materially retard the motor in reverse on lowering the load, but to stop the spinning of the axle 9 with its gears, so that the main holding brake 29, with its cooperating parts, will immediately function to itself hold the load at any desired elevation, as soon as the motor is cut off.

Having thus described this invention in connection with an illustrative embodiment thereof, to the details of which I do not desire tobe limited, what is claimed as new and what is desired to secure by Letters Patent is set forth in the appended claims.

What I claim is 1. In a hoist mechanism the combination of a power shaft, means to operate it to raise a load, two friction brakes, one to hold the load and the other controlling the actuating member of the first friction brake.

2. In an electric hoist mechanism including a main shaft, two friction brakes, one adapted to hold the load and the other friction brake cooperating with the main shaft to prevent coasting or spinning of that shaft after the current is cut off the motor.

3. In an electric hoist mechanism including a main shaft, the combination of a main brake to hold the load, a counter-shaft, a secondary or auxiliary brake to prevent the coasting or spinning of the main shaft, said secondary or auxiliary brake being operated by the counter-shaft.

4. In an electric hoist mechanism including a main shaft, the combination of a main brake to hold the load, a counter-shaft rotating in a different direction from the main shaft, a secondary or auxiliary brake to prevent th coasting or spinning of the main shaft, said secondary or auxiliary brake being automatically operated by the counter-shaft.

In an electric hoist mechanism including a main shaft, the combination of a main brake to hold the load, a brake wheel mount ed on the main shaft, a counter-shaft, a secondary or auxiliary brake member to cooperate with the brake wheel on the main shaft, said secondary or auxiliary brake member being operated by the counter shaft.

6. In an electric hoist mechanism including a main shaft, the combination of a main brake to hold the load, a brake wheel mounted on the main shaft, a counter-shaft, a secondary or auxiliary brake band adapted to cooperate with the brake wheel and a member on the counter-shaft to automatically operate th brake band.

7. In an electric hoist mechanism including a main shaft, the combination of a main brake to hold the load, a brake Wheel mounted on the main shaft, a counter-shaft, a secondary or auxiliary brake band to cooperate with the brake Wheel and a clamp on the counter-shaft to automatically operate the brake band.

8. In an electric hoist mechanism including a main shaft, the combination of a main brake to hold the load, a. brake Wheel mounted on the main shaft, a counter-shaft, a; sec- 10 ondary or auxiliary brake band to cooperate with the brake wheel and an adjustable clamp on the counter-shaft to automatically operate the brake band.

ET'HAN N. HESECOOK. /Vitnesses BENTEN IRWIN,

B. J. HANN. 

